1. Field of the Invention
The present invention relates to an intake control apparatus of an internal combustion engine for controlling amounts of intake flowing to respective combustion chambers by intake control valves respectively provided on upstream sides of intake valves of respective cylinders on branch intake paths communicated with combustion chambers of the respective cylinders.
2. Description of the Related Art
In an engine which is an internal combustion engine mounted to an automobile, an intake path and an exhaust path communicated with a combustion chamber are opened and closed by an intake valve and an exhaust valve provided at a cylinder head. An intake amount of the engine is uniquely determined by an intake air amount adjusting unit of the intake path, for example, an opening degree of a throttle valve and a rotational speed of the engine.
On the other hand, there is known a phase variable apparatus of a cam shaft advance/delay adjusting type for adjusting to advance or delay a rotational phase of a cam shaft of a valve system in accordance with an operating state of an engine. In this case, by adjusting to advance or delay a valve timing of the intake valve, a valve overlap amount of the intake valve and the exhaust valve is controlled. Thus, an amount of air introduced to a combustion chamber, or an amount of exhaust gas temporarily exhausted from the combustion chamber and flowing back to remain in the combustion chamber, that is, an inner EGR amount is made to be proper to thereby achieve an improvement in an output of the engine, emission and fuel cost or the like. JP-A-2000-130200 discloses the phase variable apparatus of the cam shaft advance/delay adjusting type.
In place of the cam advance/delay adjusting type, there is known a phase variable apparatus of an actuator drive type using an electromagnetic actuator or a hydraulic actuator. The apparatus achieves an advantage of capable of ensuring a comparatively large degree of freedom of a phase variable control since the apparatus directly controls an opening/closing timing and an opening/closing time period of the valve.
In place of the phase variable apparatus, there is known an apparatus provided with electromagnetically controlled intake control valves on upstream sides of respective intake valves on respective intake branch paths. When a plurality of the intake control valves are used, as shown in FIG. 11, intake air is made to flow to a corresponding combustion chamber at a region E1 at which an opening/closing lift line Vs of the intake control valve overlaps opening/closing lift lines Ve, Vi of an intake valve and an exhaust valve. That is, when an intake amount to the combustion chamber is adjusted to be increased or decreased, by increasing or decreasing an interval of a valve opening timing t1 and a valve closing timing t2 of the intake control valve, an intake air amount can easily be adjusted to be increased or decreased without controlling to increase or decrease lift amounts of the intake and the exhaust valves. Japanese Patent No. 2734645 discloses an example of the phase variable apparatus of the intake control valve type.
Meanwhile, according to the phase variable apparatus of the cam shaft advance/delay adjusting type, a problem that an advance/delay adjusting width of the cam shaft is comparatively narrow is liable to be posed. According to the phase variable apparatus of the actuator drive type, a problem is liable to be posed in alleviation of impact in valve seating after lifting the valve and high speed following performance. According to the phase variable apparatus of a mechanical type, constituent members tend to be complicated, and a problem is liable to be posed in high speed following performance and ensuring of a mounting space in accordance therewith.
In the case of the apparatus having the plurality of intake control valves of Japanese Patent No. 2734645, electromagnetic actuators independent from each other are used for controlling to open or close the respective intake control valves, and response speeds of the respective intake control valves are determined by functions of the electromagnetic actuators. Further, the response speeds of the respective intake control valves are substantially constant in contrast to a rotational number of an internal combustion engine and therefore, when the rotational number of the internal combustion engine is increased, the response speed in correspondence with a crank angle is reduced. Therefore, when intake introducing timings are controlled by opening or closing the respective intake control valves, delays in response of the intake control valves are liable to be produced on a high rotation side of the internal combustion engine. When the electromagnetic actuator is changed to that of a high output, the response delay is improved and the high speed following performance is promoted, however, there poses a new problem that a space of installing a large-sized electromagnetic actuator needs to be found at inside of a narrow engine room.
According to the internal combustion engine having the phase variable apparatus, by an error in fabricating the respective apparatus or the response delay, a variation is present in the introduced intake amounts to the respective combustion chambers and a technical problem is posed in how to reduce the variation.